How long does a deck last
A pressure-treated deck lasts 15 to 25 years and composite decking 25 to 30, on a frame that is usually still pine. What ends a deck is almost never the boards you walk on.
National average
$60
per sq ft
On this page
- What lasts how long
- The five things that actually decide it
- Reading your own deck
- Extending it
- Frequently asked questions
- Can I put composite decking on an old frame?
- Does composite decking really last longer?
- How do I know if my deck is safe?
- When should I replace rather than repair?
- Is a permit needed for a rebuild?
A pressure-treated pine deck lasts 15 to 25 years. Cedar lasts 15 to 20. Composite decking lasts 25 to 30, on a frame that is usually still pressure-treated pine and therefore still ages at pine's rate.
That last point is the one worth holding onto. What ends a deck is almost never the boards you walk on. It is the frame, the posts and the ledger, which nobody looks at.
What lasts how long
| Component or material | Typical life |
|---|---|
| Pressure-treated pine decking | 15 to 25 years |
| Cedar decking | 15 to 20 years |
| Redwood decking | 20 to 30 years |
| Tropical hardwood, ipe or similar | 25 to 50 years |
| Composite decking | 25 to 30 years |
| PVC decking | 30 to 50 years |
| Pressure-treated frame | 20 to 30 years |
| Ledger board, properly flashed | 25 to 35 years |
| Ledger board, unflashed | 10 to 15 years |
| Posts in ground contact | 10 to 20 years |
| Posts on brackets above concrete | 25 to 40 years |
| Concrete footings | 40 years or more |
| Galvanised fasteners | 15 to 25 years |
| Stainless fasteners | 40 years or more |
| Wood railing | 10 to 20 years |
| Aluminium or composite railing | 25 to 40 years |
| Stain finish | 2 to 5 years |
The five things that actually decide it
Flashing over the ledger. A deck with proper flashing where it meets the house lasts twice as long as one without, and the difference is a $30 piece of metal installed on day one. Unflashed ledgers rot, and they take the house's rim joist with them.
Whether the posts touch the ground. A post set in soil, or in concrete with no drainage, wicks water and rots at grade. A post on a galvanised bracket above a concrete pier stays dry and outlasts the deck.
Drainage between boards. Boards fitted tight, or with debris packed in the gaps, hold water against the joists. The joist tops are where a frame rots first, and joist tape at $0.50 to $1.50 a linear foot during construction adds years.
The fasteners. Modern pressure-treated lumber is corrosive to ordinary galvanised steel. Hot-dip galvanised or stainless is required; electro-galvanised fails. A deck whose fasteners are corroding is failing at every connection at once.
Finish, or the decision not to. A stained deck lasts longer than a bare one. A deck finished once in 2009 and never again is worse off than one never finished at all, because a failed film traps moisture.
Reading your own deck
Twenty minutes each spring:
- Screwdriver test the ledger, the rim joist behind it, joist ends, post bases and stair stringers. Soft is rot.
- Look for the flashing over the ledger. Absence is the most common finding.
- Shake the railing at the top of the stairs. Movement is a post attachment problem.
- Bounce on it. A deck that moves has a framing problem.
- Look at the fasteners for rust, backing out, or hangers fastened with the wrong nails.
- Check the boards for cupping, splitting, and soft spots around fasteners.
The frame findings are the ones that matter. Boards can be replaced; a rotten ledger is a structural repair and a collapse risk.
Extending it
- Clean and reseal on cycle: every two to four years for semi-transparent stain
- Keep debris out of the gaps, especially where a deck sits under trees
- Keep planters off the boards, or on feet, because a planter sitting flat holds water permanently
- Clear snow with a plastic shovel, and keep de-icing salt off wood
- Trim back planting so air moves under and around it
- Replace corroding fasteners before the connections loosen
A deck maintained this way reaches the top of its range. One left alone reaches the bottom.
Frequently asked questions
Can I put composite decking on an old frame?
Only if the frame is sound and the joist spacing suits it: most composite needs joists at 16 inches on centre, some at 12 for diagonal patterns. Adding joists is $100 to $300 each, and putting 30-year decking on a 20-year frame is a decision worth making deliberately.
Does composite decking really last longer?
The boards do, and they do not rot, splinter or need staining. They fade, they scratch, they get very hot in direct sun, and the early generations stained badly. The frame underneath is still wood, which is why a composite deck is not a maintenance-free deck.
How do I know if my deck is safe?
The ledger, the posts and the railing, in that order. If the ledger is unflashed or soft, or the railing moves when you push it, those are the two that fail with people on the deck. An inspection by a contractor is $150 to $400.
When should I replace rather than repair?
When the ledger or the rim joist behind it is rotten, when more than a quarter of the joists are soft, when the posts have failed at grade, or when the deck does not meet current code for railing height and stair geometry and you are opening it up anyway.
Is a permit needed for a rebuild?
For structural work, yes in almost every jurisdiction. The footing and framing inspections are the only independent check anyone will make on the parts that carry people.
Read next
Deck repair cost$500 to $3,000per projectRepairing a deck costs $500 to $3,000, typically $1,400. The question is not the boards. It is the ledger where the deck meets the house, which is where nearly every deck failure begins.
Deck staining cost$2 to $5per sq ftStaining a deck costs $1.50 to $4.00 a square foot, putting a 300 square foot deck at $450 to $1,200. The cost is not the stain; it is the preparation, and skipping it is why finishes fail in a year.
Deck railing cost$30 to $150per linear ftDeck railing costs $30 to $150 a linear foot installed. It is frequently a third of the cost of a small deck, because a small deck has almost as much perimeter as a large one.
Composite deck cost$40 to $100per sq ftA composite deck costs $40 to $100 per square foot installed, typically $60. Re-decking a sound existing frame is $20 to $45, less than half the cost of building new.
Deck cost by state$30 to $65per sq ftA pressure-treated deck costs $38 a square foot in Arkansas and $53 in Illinois. On a 300 square foot deck that is $11,400 against $15,900 for identical work.